A cobporation op



R. L. ANDREAU.

METHOD OF CHANGING ISOBORNEOL INTO CAMPHOR.

APPLICATION FILED MAY 25, I918.

1,824,140.. Patented Dec. 9,1919.

ATTORNEYS l I TE SE8 ATNT FFICEO ROLAND L. ANDREAU, OF WILMINGTON, DELAWARE, ASSIGNOR TO E. I. DU PONT DE NEMOURS AND COMPANY, OF WILMINGTON, DELAWARE, A CORPORATION OF DELAWARE.

Specification ofletters Patent.

Patented Dec. 9, 1919.

Application filed May 25, 1918. Serial No. 236,518.

To all whom it may concern:

Be it known that I, ROLAND L. ANDREAU, of Wilmington, in the county of New Castle, and in the State of Delaware, have invented a certain new and useful Improvement in Methods of Changing Isoborneol Into Camphor, and do hereby declare that the following is a full, clear, and exact description thereof.

My invention relates particularly to a process of changing iso-borneol into camphor, but has particular reference to a process of this kind as applied to the commercial production of synthetic camphor.

The object of my invention is to provide an advantageous and simple process by means of which iso-borneol may be changed into camphor without the production of any substantial quantity of undesirable decomposition products.

A further object is to provide a process of the above character in which no additional chemical reagent is needed to bring about the production of the camphor.

Further objects of my invention will appear from a detailed descr ption thereof contained hereinafter.

In general my process comprises acting upon iso-borneol by nitric acid at a comparatively low temperature and w1th the aid of an electric current.

For example I may proceed as follows:

I may heat 1,000 grams of nitric acid sp. gr. 1.40 to about 40 C. and then sprinkle 10 grams of iso-borneol on the top thereof. Two platinum terminals are now held 1nto the liquid a short distance apart and so as to extend 20 millimeters below the surface of the acid and have an electric current supplied to them of about 1.6 volts and 30 amperes. The reaction begins in a few minutes and thereafter extends through the whole mass, whereupon the electrodes are withdrawn and more iso-borneol is gradually added. Thereupon, the supernatant liquid is decanted and the camphor precipitated,

washed and dried. A practically theoretical yield is obtained in this way.

VV h1le my invention is capable of being carried out with any ordinary type of apparatus which will not be acted upon by the materials used, by way of example I will descrl'be hereinafter an example of my invent1on as carried out in a particular kind of apparatus shown in the accompanying drawings, in which;

Figure 1 is a diagrammatic representation of an apparatus which may be used in accordance with my invention; and

Fig. 2 is a perspective View of the electrodes.

Referring to the drawings, I may provide a stoneware vessel 1 having a capacity of approximately. 100 gallons, and provided .with a mechanical stirrer of stoneware 2 driven from anysuitable source of power. The vessel 1 has an inlet opening 3 for the materials to be treated, a vent 4 for any vapors produced, and a valved outlet pipe 5. A jacket 6 is provided around the tank 1 in the form of a heating or cooling tank made of wood or steel, the same being adapted to contain a body of liquid, such as water, which may be cooled or heated by means of a coil pipe 7 therein provided with hot and cold water inlet pipes 8 and 9, and an outlet pipe 10. Two platinum electrodes in the form of plates 11 and 12 acting as the positive and negative poles respectively, and separated by insulating blocks 13 and 14 bound thereto by insulating wires 15 and 16 are supplied with an electric current by means of wires 17 and 18 leadin to an ammeter 19 and a voltmeter 20. T e wires 17 and 18 are preferably supplied with a direct current at approximately 1.6 volts having a density of approximately 30 amperes. 600

ounds of nitric acid having a specific gravity of 1. 1 are introduced into the vessel 1, and the temperature thereof is raised to 40 C. The two electrodes 11 and 12 which may be of any desired size, but which are prefer.

ably one inch wide and six inches long are then introduced into the nitric acid. While the stirrer 2 is at rest, about pound of isoborneol is dropped upon the top of the immersed' electrodes, and the electric current is turned on. After a short time, thereaction will be seen to have started by the ebullition of the mass at that point with the evolution of red fumes, the electric current having decomposed the nitric acid in the vicinity thereof, so as to cause the same to react instantly upon the iso-borneol. In this way, a reaction may be started almost at ordinary temperatures. The electrodes are then removed, and the stirrer 2 is rotated while additional iso-borneol is added at the rate of one pound every few minutes, until 150 pounds of iso-borneol have been added,

the temperature being kept at approximately 40 0., by the supply of a cooling medium through the coil Camphor nitrate is formed in this manner as the reaction which has been initially started by the electric current soon becomes propagated throughout the entire mass of material. Camphor nitrate is thus formed which floats as an oil on the top of the Weak acid. The liquid layers are separated by decantation, and the camphor nitrate is drowned in a large excess of water, whereupon it breaks up to form camphor which is washed with water, dried and purified by sublimation. A practically theoretical yield is obtained.

While I have described my inventionabove in detail, I wish it to be understood that many changes may be made therein without departing from the spirit thereof. For example, the temperatures and proportions may vary to a considerable degree.

What I claim is: p I 1. The process which comprises producing camphor by oxidizing iso-borneol with a moderately concentrated nitric acid by applying thereto an electric current momentarily, and then discontinuing the application of the electric current.

'2. The process which comprises producing camphor by oxidizing iso-borneol with a moderately concentrated nitric acid and having a sp. gr. of 1.40 by applying thereto an electric current momentarily, and then discontinuingthe application of the electric current.

3. The process which comprises producing camphor by oxidizing iso-borneol with a moderately concentrated nitric acid at comparatively low temperatures, by applying thereto an electric current momentarily, and

then discontinuing the application of the electric current.

4. The process which comprises producing camphor by oxidizing iso-borneol with a moderately concentrate nitric acid and ing the application of the electric current.

nee mac having a sp. gr. of 1.40 at comparatively low temperatures by applying thereto an electric current momentarily, and then discontinumg the application of the electric current. 1 I

t 5. The process which comprises producmg camphor by oxidizing iso-borneol with a moderately concentrated nitric acid at comparatively low temperatures and not above 40 C. by applying thereto an electric current momentarily, and then discontinu- 6. The process which comprises producing camphor by oxidizing iso-borneol with a moderately concentrated nitric acid and havmg a sp. gr. of 1.40 at comparatively low temperatures and not above 40 C. by applymg thereto an electric current momentarily and then discontinuing the application of the electric current. 7. The process which comprises produclngcamphor by oxidizing iso-borneol with nitrlc acid by applying thereto an electric current momentarily, and then discontinumg the application of the electric current. 8. The process which comprises producmg camphor by oxidizing iso-borneol with a moderately concentrated nitric acid, by applying thereto an electric current momentarily, and then discontinuing the application of the electric current without adding any other catalyst.

9. The process which comprises producing camphor by oxidizing iso-borneol with a moderately concentrated nitric acid andhavmg asp. gr. of 1.40, by applying thereto an electriccurrent momentarily, and then discontinuing the application of the electric current without adding any other catalyst. 10. The process which comprises producmg camphor by oxidizing iso-borneol with a moderately concentrated nitric acid at comparatively low temperatures, by applylng thereto an electric current momentarily, and then discontinuing the application of the electric current without adding any other catalyst.

11. The process which comprises producmg camphor by oxidizing iso-borneol with a moderately concentrated nitric acid and having a sp. gr. of 1.40 at comparatively low temperatures, by applying thereto an 115 electric current momentarily, and then discontinuing the application of the electric current without adding any other catalyst.

' 12. The process which comprises producmg camphor by oxidizing iso-borneol with 120 a moderately concentrated nitric acid at comparatively low temperatures and not above 40 C., by applying thereto an electric current momentarily, and then discontinuing the application of the electric current with- 125 out adding any other catalyst. I

13. The process which comprises producing camphor by oxidizing iso-borneol with a moderately concentrated nitric acid and having a sp. gr. of 1.40 at comparatively low temperatures and not above 10 0., by applying thereto an electric current momentarily, and then discontinuing the application of the electric current without adding any other catalyst.

14. The process which comprises producing camphor by oxidizing iso-borneol with nitric acid by applying thereto an electric current momentarily, and then discontinuing the application of the electric current without adding any other catalyst.

In testimony that I claim the foregoing I have hereunto set my'hand.

ROLAND L. ANDREAU.

Witnesses-z ARTHUR P. TAUBERG, J. H. WALLIS. 

